The present invention relates to a hybrid pipette usable in either of two operating modes, i.e. a manual operation mode and a motor-driven operation mode, by switching between the two modes at will.
Pipettes are roughly divided into two types according to their operating methods, i.e. hand-operated (manual) pipettes and motor-driven pipettes. The manual pipettes provide high reliability with a simple structure and allow the suction/discharge speed to be controlled delicately and hence exhibit high accuracy and superior reproducibility even when pipetting liquids having different volumes and also pipetting liquids having different viscosity. Moreover, the costs are favorably low. Therefore, the manual pipettes are in widespread use.
On the other hand, with the motor-driven pipettes, it is difficult to control the suction/discharge speed delicately in the pipetting operation. Conversely, the operation of the pipettes is constant and stable. In addition, the motor-driven pipettes have an advantage in that they do not require much physical strength even when used for a long period of time.
However, the manual pipettes may cause differences in manual operation among individuals and require some practice to perform a stable pipetting operation. Moreover, a great deal of physical strength is needed to treat a large number of specimens. In addition, the manual pipettes perform only simple pipetting operation and do no include various other functions.
The motor-driven pipettes can solve the problems caused by the manual pipettes but are incapable of delicately controlling a pipetting operation. That is, it is difficult to use them in a manner other than the predetermined manner of using. Furthermore, the production cost is unfavorably high, and the motor-driven pipettes cannot continuously be used for a long period of time because of the limited battery lifetime.
Accordingly, an object of the present invention is to provide a hybrid pipette selectively usable in either of two operating modes, i.e. a manual operation mode and a motor-driven operation mode, so that it becomes possible to control a pipetting operation delicately in the manual operation mode and it is also possible to perform a stable pipetting operation and to treat a large number of specimens in the motor-driven operation mode.
Another object of the present invention is to provide a hybrid pipette made selectively usable in either of the above two operating modes simply by providing a single engagement member.
Still another object of the present invention is to provide a hybrid pipette in which an electric motor and a slide shaft are provided on different axes, so that it is possible to readily provide a brake mechanism for braking the rotation of the electric motor and a transmission gear mechanism for decelerating the rotation of the electric motor.
A further object of the present invention is to provide a hybrid pipette in which an electric motor and a slide shaft are coaxially provided, so that it is possible to reduce the diameter of the pipette itself and hence possible to reduce the overall size of the hybrid pipette.
A still further object of the present invention is to provide a hybrid pipette in which in the motor-driven operation mode in particular, a tubular threaded member, a slide shaft and a plunger move downward in a state where the relative position of the three members is kept constant, so that there is no need to apply compressive force to a spring provided between the slide shaft and the plunger, whereby the driving torque of the electric motor can be reduced correspondingly.
According to a first aspect thereof, the present invention provides a hybrid pipette including a pipette casing and a slide shaft that is vertically movable in response to the operation of a pushbutton. A plunger is disposed below the slide shaft and urged upwardly by a spring. An engagement member is coaxially and movably fitted on the slide shaft and extends through a hole of the pipette casing so as to be movable at least vertically. An electric motor is provided on an axis different from the axis of the slide shaft and operatively engaged with the engagement member. In a manual operation mode, the slide shaft and the plunger move vertically in response to the operation of the pushbutton to perform suction and discharge of a liquid. In a motor-driven operation mode, the engagement member is driven to move vertically by the electric motor, whereby the plunger is moved vertically to perform suction and discharge of a liquid.
Preferably, the engagement member is a tubular threaded member having an external thread on the outer periphery thereof, and the hole of the pipette casing is an internally threaded hole. The tubular threaded member is in thread engagement with the internally threaded hole. The tubular threaded member is driven to rotate by the electric motor, thereby moving vertically through thread engagement with the internally threaded hole.
Preferably, the engagement member is a rack member having an axially extending rack on the outer periphery thereof. The rack member extends through the hole of the pipette casing and is moved vertically by a pinion driven by the electric motor.
Preferably, a transmission gear mechanism is provided between the electric motor and the engagement member.
Preferably, the electric motor is a direct-current motor and provided with a brake mechanism, or said electric motor may otherwise be a pulse motor.
Preferably, the hybrid pipette further includes a battery for driving the electric motor.
The hybrid pipette according to the first aspect of the present invention provides the following advantages.
Because a single pipette is selectively usable in either of two operating modes, i.e. a manual operation mode and a motor-driven operation mode, it is possible to control pipetting operation delicately in the manual operation mode and it is also possible to perform stable pipetting operation in the motor-driven operation mode. Moreover, because the motor-driven operation mode does not require much physical strength, it is possible to treat a large number of specimens easily.
It is only necessary to provide a single engagement member to attain a pipette which is selectively usable in either of two operating modes, i.e. a manual operation mode and a motor-driven operation mode. Therefore, the arrangement of the pipette is extremely simple.
Furthermore, because the electric motor and the slide shaft are provided on different axes, it is possible to readily provide a brake mechanism for braking the rotation of the electric motor and a transmission gear mechanism for decelerating the rotation of the electric motor. Accordingly, the hybrid pipette has wide applicability.
According to a second aspect thereof, the present invention provides a hybrid pipette including a pipette casing and a slide shaft that is vertically movable in response to the operation of a pushbutton. A plunger is disposed below the slide shaft and urged upwardly by a spring. An electric motor is provided in coaxial relation to the slide shaft. A tubular threaded member with an external thread on the outer periphery thereof is coaxially and movably fitted on the slide shaft and vertically movably extends through a central internally threaded hole in the electric motor. In a manual operation mode, the slide shaft and the plunger move vertically in response to the operation of the pushbutton to perform suction and discharge of a liquid. In a motor-driven operation mode, the tubular threaded member is driven to move vertically by the electric motor, whereby the plunger is moved vertically to perform suction and discharge of a liquid.
Preferably, the electric motor is a direct-current motor and provided with a brake mechanism, or said electric motor may otherwise be a pulse motor.
Preferably, the hybrid pipette further includes a battery for driving the electric motor.
The hybrid pipette according to the second aspect of the present invention provides the following advantage in addition to the above-described advantages.
When the electric motor and the slide shaft are coaxially provided, the tubular threaded member also severs as a rotor of the motor. Therefore, it is possible to simplify the arrangement and to reduce costs. Furthermore, it is possible to reduce the diameter of the pipette itself and to minimize the overall size of the hybrid pipette.
According to a third aspect thereof, the present invention provides a hybrid pipette including a pipette casing and a slide shaft vertically movable in response to the operation of a pushbutton. A plunger is disposed below the slide shaft. The plunger is vertically movable together with the slide shaft as one unit. An electric motor is provided in coaxial relation to the slide shaft. The electric motor has an internally threaded hole. A tubular threaded member with an external thread on the outer periphery thereof is coaxially and movably fitted on the slide shaft and is thread-engaged with the internally threaded hole in the electric motor to allow said slide shaft to move vertically. At least one spring is interposed between a predetermined position on the slide shaft and the tubular threaded member to urge the slide shaft and the plunger upwardly so that a predetermined portion of the slide shaft or the plunger abuts against a predetermined portion of the tubular threaded member or the pipette casing. In a manual operation mode, the slide shaft and the plunger move vertically in response to the operation of the pushbutton to perform suction and discharge of a liquid. In a motor-driven operation mode, the tubular threaded member is driven to move vertically by the electric motor, whereby the plunger is moved vertically to perform suction and discharge of a liquid.
Preferably, the at least one spring is interposed between the upper end of the tubular threaded member projecting above the electric motor and an upper portion of the slide shaft within the pipette casing. However, the present invention is not necessarily limited to this arrangement. The at least one spring may be interposed between a predetermined portion of the tubular threaded member and a predetermined portion of the slide shaft or the plunger below the electric motor.
Preferably, the slide shaft and the plunger are fabricated integrally as a single member.
Alternatively, the slide shaft and the plunger may be fabricated as separate members and joined together as one unit by screwing one of them into the other or by using a pin.
The hybrid pipette according to the third aspect of the present invention provides the following advantages in addition to the above-described advantages.
In the motor-driven operation mode in particular, the tubular threaded member, the slide shaft and the plunger move downward in a state where relative position of said three members is kept constant. Accordingly, there is no need to apply compressive force to the spring provided between the slide shaft and the plunger. Therefore, the driving torque of the electric motor can be reduced correspondingly. Thus, it is possible to reduce the size of the electric motor and to minimize the overall size of the hybrid pipette and hence possible to increase the lifetime of the battery for driving the motor.
Accordingly, it has become possible to use a pulse motor as an electric motor which can present relatively small driving torque, thereby presenting large selectivity of motors. In addition, when a pulse motor is used, there is no need to use a brake mechanism, thereby capable of further minimizing the size of the hybrid pipette.
If the slide shaft and the plunger are prepared as separate members and then joined together, the pipette assembling operation is facilitated.
Preferably, the electric motor is a direct-current motor and provided with a brake mechanism, or said electric motor may otherwise be a pulse motor.
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings.